docs: def deroot(self, label='OLDROOT'):
          '''If the tree has a root edge, drop the edge to be a child of the root node
  
          Args:
              ``label`` (``str``): The desired label of the new child
          '''
          if self.root.edge_length is not None:
              self.root.add_child(Node(edge_length=self.root.edge_length,label=label))
              self.root.edge_length = None